Episodes of ventricular tachyarrhythmia (VTA) are lethal arrhythmia, namely ventricular fibrillation and ventricular tachycardia, which may accelerate into ventricular fibrillation. Drug therapies may be used, but these anti-arrhythmic drugs often have undesirable side effects. Clinical experience has shown that at an acceptable level, these anti-arrhythmic drugs may reduce but not completely eliminate episodes of VTA. An effective device for treating, as opposed to preventing, VTA is the implantable cardioverter defibrillator (ICD). An ICD may be implanted in a patient at risk of sudden cardiac attack, for example, by an episode of VTA. However, an ICD may treat, but does not prevent episodes of VTA.